In the modern manufacture of both softbound and hardbound books, obviously important objectives are the rate of books produced and consistent and reliable high quality of the products. In recent years there has been good progress in the development of various procedures and machinery for the manufacture of books at much higher rates than previously considered possible, i.e. one hundred books per minute as the output delivery rate. Typically the books discharged from a building-in machine, as described in applicant's copending application, Ser. No. 379,037, filed May 17, 1982, are all in the same orientation, which means that the spine or backbone of each book is aligned with the spine of the next. The obvious next step is for such books to be stacked for packaging in cartons and final shipment.
It has been found that stacking of books whose spines are similarly aligned leads to an undesirable situation, since the spine edge of each book is usally thicker than the opposite free edges of the cover and the pages. Not only are stacks of such books somewhat unstable as they tend to lean and tip, but any particular stack would have greater height than a stack comprising the same number of books which are oriented alternately so that odd numbered books have the original orientation and even numbered books are rotated 180.degree.. With the spines so alternated on opposite edges of the stack, the stacks will have reduced height and thus occupy less space on the equipment, in the factory and in the cartons or other packaging used.
Once it was determined that the books must be stacked in alternate orientation as described above, the prior art discloses manual techniques eventually replaced by mechanical devices. Where workers manually lift, rotate and put down each appropriate book to create the proper stacking orientation the result is unacceptable in a high speed mass production assembly line. The obvious development for this problem of a mechanical device, typically based upon a Geneva mechanism which lifts and rotates appropriate alternate books and puts them down, eliminates the manual aspect; however, such apparatus still has a number of severe limitations, primarily in that the device must grasp a moving book, rotate and then reposition such book on a fast moving conveyor. Geneva-type mechanisms of the prior art have the inherent limitation that the device is continually stopping and starting, which means average velocity will be greatly reduced, with the additional restriction on velocity due to acceleration and deceleration limitation. Furthermore, it is expensive and complicated to cause a book, moving at a velocity of 100 books per minute or 85-100 feet per minute, to stop, rotate 180.degree., and to reattain the prior velocity while being precisely relocated and oriented on a moving belt. Accordingly, known mechanisms in the prior art for rotating books cause the overall process to have significantly reduced speed from that of the infeed conveyor delivering books from a building-in machine. Consequently the final stacking and packaging stages are reduced in speed to that of the book rotation mechanism and the great benefits of high speed manufacture are defeated by an interim phase of manufacture.
The present invention provides a solution to this problem in the form of a book turnover device which provides for the 180.degree. rotation without any loss in speed of the books delivered by the infeed conveyor at its maximum speed. An optional combination with the turnover device is a stack accumulator which forms said books into stacks, each stack formed from the bottom upwardly. A summary of the invention followed by a detailed description of the preferred embodiment follows below.